The present invention relates generally to farm implements and, more particularly, to tillage implements.
Tillage is an agricultural practice in which the soil (“seedbed”) is prepared for subsequent seeding. The seedbed is prepared by agitating the soil using mechanical agitations, such as by digging, stirring, or overturning. Tillage loosens and aerates the top layer of soil. It also helps in the mixing of crop residue, organic matter, and nutrients throughout the soil. Tillage is also effective in uprooting and destroying invasive plantings, e.g., weeds, and also is effective in drying the soil before seeding.
Tillage is often classified into two types: primary and secondary. Primary tillage is typically carried out immediately or shortly after harvest to mix the crop residue with the soil. Primary tillage is also done at greater soil depths and leaves behind a rough and somewhat clumpy surface. Secondary tillage, on the other hand, is typically carried out immediately before seeding. It is carried out at shallower soil depths and yields a smoother surface finish. A couple of the principle aims of secondary tillage is to (1) reduce soil compaction that may have occurred over the winter and (2) dry out the soil.
While tillage can be classified into two different types, in general, there are three different types of tillage systems. Intensive tillage systems leave less than 15% crop residue cover or less than 500 pounds per acre (560 kg/ha) of small grain residue. These types of tillage systems are often referred to as conventional tillage systems. These systems involve often multiple operations with implements such as a mold board, disk, and/or chisel plow. Then a finisher with a harrow, rolling basket, and cutter can be used to prepare the seed bed. Reduced tillage systems leave between 15 and 30% residue cover on the soil or 500 to 1000 pounds per acre (560 to 1100 kg/ha) of small grain residue during the critical erosion period. This may involve the use of a chisel plow, field cultivators, or other implements. The third type of tillage systems are conservative tillage systems. Conservation tillage systems are methods of soil tillage which leave a minimum of 30% of crop residue on the soil surface or at least 1,000 lb/ac (1,100 kg/ha) of small grain residue on the surface during the critical soil erosion period. This slows water movement, which reduces the amount of soil erosion. Conservation tillage systems also provide the benefit of reduced fuel consumption and soil compaction.
One type of conservation tillage system is strip-till, which is intended to combine the soil drying and warming benefits of conventional tillage with the soil-protecting advantages of no-till by disturbing only the portion of the soil that is to contain the seed row. Another advantage of strip-till is that many of the strip-till machines can also apply chemicals and fertilizer at the same time as tillage.
A conventional strip-till machine or implement consists of a toolbar with a variety of working tools mounted thereto. These working tools typically include disc coulters, shanks, sealers (“berm builders”), and conditioning baskets. The disc coulters plough through and cut the crop reside and the shanks cut through the soil. This cutting through the soil causes the soil to be lifted whereupon the sealers, which are typically discs often arranged in tandem and angled relative to the direction of travel, push the raised soil toward an imaginary centerline between the two discs. The pushed soil effectively forms a berm. For those machines so-equipped, fertilizer or chemicals are placed in the soil as the shanks cut through the soil resulting in the berm containing a mixture of soil and chemicals and/or fertilizer. During planting, seeds will be deposited onto the nutrient-rich berms.
The sealers, as noted above, are typically discs (also referred to as “disc blades”). Each disc has an inner or concave surface and an outer or convex surface. For the tandem discs, the raised soil is pushed by the inner surfaces toward the aforementioned centerline to form a berm generally along the centerline. One of the drawbacks of conventional sealers is that soil tends to collect and build up on the inside or concave surface of the disc, as illustrated in FIG. 1. Soil tends to build up on the concave surface of the disc, starting from the center of the disc and continuing to build in an outwardly radial direction to the outer edge of the disc. The soil build-up is much more rapid with wetter/stickier soils or soil conditions. Wetter conditions are more prevalent in the late fall of the year with fall rains, reduced heat units to dry the soil, and reduced hours of sunlight. As much of the strip tillage takes place in the late fall, soil buildup on the sealers can be quite common.
When soil builds up on the concave side of the sealer disc, the disc becomes more like a roller than a blade and, as a result, the disc begins to ride over the lifted soil rather than direct the soil inward to build a berm. In strip-till, berm formation and berm height is critical and thus it is imperative that the berm builder disc be substantially free of build-up.